Method for patterning a photosensitive layer

ABSTRACT

The method of patterning a photosensitive layer includes providing a substrate including a first layer formed thereon, treating the substrate including the first layer with cations, forming a first photosensitive layer over the first layer, patterning the first photosensitive layer to form a first pattern, treating the first pattern with cations, forming a second photosensitive layer over the treated first pattern, patterning the second photosensitive layer to form a second pattern, and processing the first layer using the first and second patterns as a mask.

BACKGROUND

The present disclosure relates generally to semiconductor manufactureand, more particularly, to a method for patterning a photosensitivelayer in semiconductor manufacture.

Photolithography is frequently used for forming the components ofintegrated circuits (IC). Generally, an exposure tool includes aphotomask or reticle, through which light beams pass through and arefocused by a projection lens onto a wafer, resulting in an image ofdevice features in a photosensitive layer such as a photoresist layerformed on the wafer. There has been a continued increase in the densityof devices that can be placed on a chip and as a result, the printing ofdevice feature patterns with an extremely small pitch is required.However, there is a minimum pitch printing resolution limit that isdetermined by the wavelength of the light beam and the numericalaperture of the exposure tool. The pitch is the distance from one devicefeature to an adjacent device feature. If the pitch becomes too small,the projected image may be distorted by so called “proximity effects”that are associated with the diffraction of light. One method forforming such device features includes two photolithography processes andtwo etching processes. For example, a first mask is formed to provide afirst pattern with substantially linear features. The substrate is thenetched according to this first pattern to form substantially linearfeatures. The first mask is then removed from the substrate. A secondmask may then be formed to provide a second pattern for gaps in thepreviously formed substantially linear features. The substrate may thenbe etched according to this second pattern. The numerous steps requiredadd costs to the fabrication including, for example, increasedcomplexity of the processing and increased cycle time.

Therefore, what is needed is a simple and cost-effective method forpatterning a photosensitive layer in semiconductor manufacture forprocess technologies of 45 nm and below.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isemphasized that, in accordance with the standard practice in theindustry, various features are not drawn to scale. In fact, thedimensions of the various features may be arbitrarily increased orreduced for clarity of discussion.

FIG. 1 is a flowchart for a method for pattering a photosensitive layerin semiconductor manufacture according to various aspects of the presentdisclosure.

FIG. 2 is a diagrammatic view of a semiconductor device being processedaccording to the method of FIG. 1.

FIG. 3 is a flowchart of an alternative method for patterning aphotosensitive layer in semiconductor manufacture according to variousaspects of the present disclosure.

FIG. 4 is a diagrammatic view of a semiconductor device being processedaccording to the method of FIG. 3.

FIG. 5 is a top view of a line pattern that may be formed by the methodsof FIGS. 1 and 3.

FIG. 6 is a top view of a hole pattern that may be formed by the methodsof FIGS. 1 and 3.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof various embodiments. Specific examples of components and arrangementsare described below to simplify the present disclosure. These are, ofcourse, merely examples and are not intended to be limiting. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.Moreover, the formation of a first feature over or on a second featurein the description that follows may include embodiments in which thefirst and second features are formed in direct contact, and may alsoinclude embodiments in which additional features may be formedinterposing the first and second features, such that the first andsecond features may not be in direct contact.

Referring to FIG. 1, illustrated is flowchart of a method 100 forpatterning a photosensitive layer according to various aspects of thepresent disclosure. Also referring to FIG. 2, illustrated arediagrammatic views of a semiconductor device 200 being processedaccording to the method 100 of FIG. 1. The method 100 begins with step102 in which a substrate 202 may be provided with a first layer 204formed thereon. The substrate 202 may include an elementarysemiconductor (such as crystal silicon, polycrystalline silicon,amorphous silicon and germanium), a compound semiconductor (such assilicon carbide and gallium arsenic), an alloy semiconductor (such assilicon germanium, gallium arsenide phosphide, aluminum indium arsenide,aluminum gallium arsenide and gallium indium phosphide) and/orcombinations thereof. In other examples, compound semiconductorsubstrate may include a multiple silicon structure, or the siliconsubstrate may include a multilayer compound semiconductor structure. Thesubstrate 202 may also include an epitaxial layer (epilayer) overlying abulk semiconductor.

The first layer 204 may include a material layer to be processed and/orpatterned to form various microelectronic features such as interconnectlines, contacts, vias, polygates, and other features known in the art.For example, the first layer 204 may include a silicon, silicon oxide(SiO2), silicon oxynitride (SiON), organic material, conductivematerial, low-k dielectric material, and other suitable material. Thefirst layer 204 may be formed by chemical vapor deposition (CVD), spincoating, or other suitable techniques known in the art. Additionally, ananti-reflective coating (ARC) (not shown) including a bottomanti-reflective coating (BARC) layer may be formed over the substrate202. The use of the BARC layer in advance photolithography enhances thecontrol of critical dimensions (CD) by suppressing reflective notching,standing wave effects, and a swing ratio caused by thin filminterference.

The method 100 continues with step 104 in which the substrate 202including the first layer 204 may be treated 206 with cations. Thecations may be provided by performing a cation implantation process. Theimplantation process may implant cations to the surface of the firstlayer 204. The cations may include B cations. Alternatively, the cationsmay optionally include H cations. Further, the cations may includeelements such as Al, Ga, In, N, P, As, Sb, C, Si, Ge, Sn, and alsoincluding their compunds. The dosage of implanted cations may range fromabout 1e⁹ to about 1e¹⁵ cm⁻². The implantation energy may range fromabout 1 to about 1M keV. The above-described ion implantation settingsare given merely as examples and should not be used to unduly limit thescope and application of this process.

Alternatively, the substrate 202 including the first layer 204 mayoptionally be treated 206 by performing a cation plasma treatment undersuitable conditions. A number of suitable plasma gases may be used, suchas gases including B cations. Alternatively, the gases may optionallyinclude H cations. Further, the gases may include other suitable cationssuch as He, C, N, O, F, Cl, Br, Ne, Ar, and also including theircompounds. The frequency for the plasm treatment may range from about 10to about 200 MHz. The reaction power of the plasma chamber may rangeabout 100 to about 3000 Watts. The above-described plasma treatmentsettings are given merely as examples and should not be used to undulylimit the scope and application of this process.

The method 100 continues with step 106 in which a first photosensitivelayer 208 may be formed over the first layer 204. The treatment with thecations from the previous step 104 has been observed to increaseadhesion between the first photosensitive layer 208 and the first layer204 and thus, improving the photolithography process that follows below.The first photosensitive layer 208 may include a photoresist or resistlayer. The resist may include a positive or negative type resist. Thefirst photosensitive layer 208 may be formed by spin coating or othersuitable process. Alternatively, the first photosensitive layer 208 mayoptionally be treated with cations as discussed above.

The method 100 continues with step 108 in which the first photosensitivelayer 208 may be patterned to form a first pattern 210. The firstphotosensitive layer 208 may be patterned by a photolithography processincluding soft-baking, exposure, post-baking, developing, rinsing,drying, and other suitable processes. The photolithography process isknown in the art and thus, not described in detail herein.

Additionally, the photolithography process may optionally include animmersion lithography process. The first pattern 210 may include a linepattern configured to form interconnects lines. The line pattern mayinclude a pitch that may be limited by a printing resolution of thephotolithography system. The pitch corresponds to the spacing betweenadjacent lines in the line pattern. The printing resolution may belimited by various factors such as the wavelength of the radiationsource and configuration of the lens system.

The method 100 continues with step 110 in which the first pattern 210may be treated 212 to form a static layer. The first pattern 210 may betreated and stabilized so that subsequent processing as described belowdoes not adversely alter the first pattern. The static layer of thefirst pattern 210 may be formed by various techniques. For example, thestatic layer may be formed by a cation implantation process similar tothe process disclosed in step 104. Alternatively, the static layer mayoptionally be formed by a cation plasma treatment similar to the processdisclosed in step 104. Further, the static layer may also be formed byUV curing, baking, and/or E-beam processing.

The method 100 continues with step 112 in which a second photosensitivelayer 216 may be formed over the substrate 202. The secondphotosensitive layer 216 may be similar to the first photosensitivelayer 208. The second photosensitive layer 216 may be formed by a spincoating or suitable process. As such, the second photosensitive layer216 substantially covers the first layer 204 including gaps within thefirst pattern 210.

The method 100 continues with step 114 in which the secondphotosensitive layer 216 may be patterned to form a second pattern 218.The second photosensitive layer 216 may be patterned by aphotolithography process similar to the one disclosed in previous step108. The second pattern 218 may also include a line pattern with linesdisposed within the gaps of the first pattern 210. The second pattern218 may include a pitch that is similar to the first pattern 210.Accordingly, the first pattern 210 and second pattern 218 may combine toform a final pattern 220 that has a pitch that is substantially one-havethe pitch of the first pattern and/or second pattern. The method 100continues with step 116 in which the first layer 204 may be processedusing the first pattern 210 and second pattern 218 as a photomask ormask. For example, the first layer 204 may be etched to form a finalline pattern 222 on the substrate 202. Thus, the method 100 can beimplemented for forming features in 45 nm and below process technologieswith current photolithography equipment and materials.

Referring to FIG. 3, illustrated is a flowchart of a method 300 forpatterning a photosensitive layer according to various aspects of thepresent disclosure. Also referring to FIG. 4, illustrated arediagrammatic views of a semiconductor device 400 being processedaccording to the method 300 of FIG. 3. The method 300 begins with step302 in which a substrate 402 may be provided with a first photosensitivelayer 404 formed thereon. The substrate 402 may be similar to thesubstrate 202 of FIG. 2. The substrate 402 may include a process layerto be processed to form various device features such as interconnectlines, contacts, vias, gate electrodes, doped regions, and otherfeatures known in the art. For example, the process layer may include asilicon, silicon oxide (SiO2), silicon oxynitride (SiON), organicmaterial, conductive material, low-k dielectric material, and othersuitable material. Additionally, an anti-reflective coating (ARC) (notshown) including a bottom anti-reflective coating (BARC) layer may beformed over the substrate 202. The use of the BARC layer in advancephotolithography enhances the control of critical dimensions (CD) bysuppressing reflective notching, standing wave effects, and a swingratio caused by thin film interference.

The first photosensitive layer 404 may include a photoresist or resistlayer. The resist may include a positive or negative type resist. Thefirst photosensitive layer 404 may be formed by spin coating or othersuitable process. The method 300 continues with step 304 in which thefirst photosensitive layer 404 may be patterned to form a first pattern406. The first photosensitive layer 404 may be patterned by aphotolithography process including soft-baking, exposure, post-baking,developing, rinsing, drying, and other suitable processes. Thephotolithography process is known in the art and thus, not described indetail herein. Additionally, the photolithography process may optionallyinclude an immersion lithography process. The first pattern 406 mayinclude a line pattern similar to the line pattern in FIG. 2.

The method 300 continues with step 306 in which the substrate 402including the first pattern 406 may be treated 408 with cations. Thefirst pattern 406 may be treated and stabilized so that subsequentprocessing as described below does not adversely alter the firstpattern. The cations may be provided by performing a cation implantationprocess. The implantation process may implant cations to the surface ofthe substrate 402 including the first pattern 406. The cations mayinclude B cations. Alternatively, the cations may optionally include Hcations. Further, the cations may include elements such as Al, Ga, In,N, P, As, Sb, C, Si, Ge, Sn, including their compunds. The dosage ofimplanted cations may range from about 1e⁹ to about 1e¹⁵ cm⁻², forexample. The implantation energy may range from about 1 to about 1 MkeV,for example. The above-described ion implantation settings are givenmerely as examples and should not be used to unduly limit the scope andapplication of this process.

Alternatively, the substrate 402 including the first pattern 406 mayoptionally be treated 408 by performing a cation plasma treatment undersuitable conditions. A number of suitable plasma gases may be used, suchas gases including B cations. Alternatively, the gases may optionallyinclude H cations. Further, the gases may include other suitable cationssuch as He, C, N, O, F, Cl, Br, Ne, Ar, including their compounds. Thefrequency for the plasm treatment may range from about 10 to about 200MHz. The reaction power of the plasma chamber may range about 100 toabout 3000 Watts. The above-described plasma treatment settings aregiven merely as examples and should not be used to unduly limit thescope and application of this process.

The method 300 continues with step 308 in which a second photosensitivelayer 410 may be formed over the substrate 402. The secondphotosensitive layer 410 may be similar to the first photosensitivelayer 404. The second photosensitive layer 410 may be formed by a spincoating or suitable process. As such, the second photosensitive layer410 substantially covers the substrate 402 including gaps within thefirst pattern 406.

The method 300 continues with step 310 in which the secondphotosensitive layer 408 may be patterned to form a second pattern 412.The second photosensitive layer 408 may be patterned by aphotolithography process similar to the one disclosed in previous step304. The second pattern 412 may also include a line pattern with linesdisposed within the gaps of the first pattern 406. The second pattern412 may include a pitch that is similar to the first pattern 406.Accordingly, the first pattern 406 and second pattern 412 may combine toform a final pattern 414 that has a pitch that is substantially smaller(e.g., one-half) than the pitch of the first pattern and/or secondpattern. The method 300 continues with step 312 in which the substrate402 may be processed using the first pattern 406 and second pattern 412as a photomask or mask. For example, the substrate 402 may be etched toform a final line pattern 420. Thus, the method 300 can be implementedfor forming features in process technologies of 45 nm and below withcurrent photolithography equipment and materials.

Referring to FIG. 5, illustrated is a top view of a line pattern 500that may be formed in a photosensitive layer by the methods 100 and 300of FIGS. 1 and 3, respectively. The line pattern 500 includes a firstline pattern 510 and a second line pattern 520. The first line pattern510 includes parallel lines that have a first pitch 530, and the secondline pattern 520 includes parallel lines that have a second pitch 540.By combining the first 510 and second 520 line patterns, the linepattern 500 includes a pitch 550 that is smaller than the first 530 andsecond 540 pitches. It has been observed that the methods 100 and 300are capable of forming a line pattern 560 on a substrate that has apitch of about 80 nm including line widths of about 45.5 nm.

Referring to FIG. 6, illustrated is a top view of a hole pattern 600that may be formed in a photosensitive layer by the methods of 100 and300 of FIGS. 1 and 3, respectively. The hole pattern 600 includes afirst line pattern 610 and a second line pattern 620. The first linepattern 610 includes parallel lines in a first direction, and the secondline pattern 620 includes parallel lines in a second direction that isperpendicular to the first direction. By combining the first 610 andsecond 620 line patterns, the hole pattern 600 includes openings 630that are created in gaps of the first and second line patterns. As such,an underlying material layer such as a dielectric layer may be etchedusing the hole pattern 600 as a photomask or mask to form holes in thedielectric layer for contacts, vias, or other suitable features. It hasbeen observed that the methods 100 and 300 are cable of forming a holepattern 640 that has a pitch of about 110 nm including holes with acritical dimension (CD) of about 52.6 nm, and/or a hole pattern 650 thathas a pitch of about 100 nm including holes with a CD of about 41.2 nm.

In summary, the present disclosure provides a method for patterning aphotosensitive layer in semiconductor manufacture which includes thesteps of: providing a substrate including a first layer formed thereon;treating the substrate including the first layer with cations; forming afirst photosensitive layer over the first layer; patterning the firstphotosensitive layer to form a first pattern; treating the first patternwith cations; forming a second photosensitive layer over the treatedfirst pattern; patterning the second photosensitive layer to form asecond pattern; and processing the first layer using the first andsecond patterns as a mask. In some embodiments, the steps of treatingthe substrate including the first layer with cations and treating thefirst pattern with cations include performing a cation implantationprocess. In other embodiments, the cation implantation process utilizescations selected from the group consisting of: B, H, Al, Ga, In, N, P,As, Sb, C, Si, Ge, and Sn. In some other embodiments, the cationimplantation process includes a dosage between 1E9 to about 1E15 cm⁻².In still other embodiments, the cation implantation process includes anenergy between 1 keV to about 1M keV.

In other embodiments, the steps of treating the substrate including thefirst layer with cations and treating the first pattern with cationsinclude performing a cation plasma treatment. In some other embodiments,the cation plasma treatment utilizes cations selected from the groupconsisting of: B, H, He, C, N, O, F, Cl, Br, Ne, and Ar. In otherembodiments, the step of providing the substrate including the firstlayer includes configuring the first layer to be selected from the groupconsisting of: silicon, silicon oxide, silicon oxynitride, organicmaterial, conductive material, and low-k dielectric material. In stillother embodiments, the step of processing the first layer using thefirst and second patterns as the mask includes etching the first layerto form a line pattern. In some other embodiments, the step ofprocessing the first layer using the first and second patterns as themask includes etching the first layer to form a hole pattern. In otherembodiments, the step of providing the substrate including the firstlayer further includes providing an anti-reflective coating (ARC) overthe first layer.

In another embodiment, a method for fabricating a semiconductor deviceincludes the steps of: providing a substrate; forming a firstphotosensitive layer over the substrate; treating the firstphotosensitive layer with cations; patterning the first photosensitivelayer to form a first pattern over the substrate; treating the firstpattern with cations; forming a second photosensitive layer over thesubstrate and the first pattern; patterning the second photosensitivelayer to form a second pattern over the substrate; and processing thesubstrate using the first and second patterns as a mask. The step oftreating the first photosensitive layer and the first pattern withcations includes performing a cation implantation process or byperforming a cation plasma process. In some embodiments, the step oftreating the first photosensitive layer and the first pattern withcations includes treating the first photosensitive layer and firstpattern with boron cations or hydrogen cations. In some otherembodiments, the cation implantation process utilizes elements selectedfrom the group consisting of: Al, Ga, In, N, P, As, Sb, C, Si, Ge, andSn. In still other embodiments, the cation plasma process utilizeselements selected from the group consisting of: He, C, N, O, F, Cl, Br,Ne, and Ar. In other embodiments, the step of providing the substratefurther includes providing an anti-reflective coating (ARC) over thesubstrate.

In yet another embodiment, a method is provided for semiconductormanufacturing which includes the steps of: providing a substrateincluding a process layer formed thereon; treating the substrateincluding the process layer by performing one of a cation implantationprocess and a cation plasma process; forming a first photoresist layerover the process layer; patterning the first photoresist layer to form afirst pattern; treating the first pattern; forming a second photoresistlayer over the substrate and the first pattern; patterning the secondphotoresist layer to form a second pattern; and etching the processlayer using the first and second patterns as a mask. In someembodiments, the cation implantation process utilizes cations selectedfrom the group consisting of: B, H, Al, Ga, In, N, P, As, Sb, C, Si, Ge,and Sn. In some other embodiments, the cation plasma process utilizescations selected from the group consisting of: B, H, He, C, N, O, F, Cl,Br, Ne, and Ar. In still other embodiments, the treating the firstpattern includes treating the first pattern by performing one of animplant process, a plasma process, an UV curing process, an e-beamprocess, and a baking process.

Aspects of the present disclosure are best understood from the followingabove description when read with the accompanying figures. It isemphasized that, in accordance with the standard practice in theindustry, various features are not drawn to scale. In fact, thedimensions of the various features may be arbitrarily increased orreduced for clarity of discussion. It is also emphasized that thedrawings appended illustrate only typical embodiments of this inventionand are therefore not to be considered limiting in scope, for theinvention may apply equally well to other embodiments.

Although only a few exemplary embodiments of this invention have beendescribed in detail above, those skilled in the art will readilyappreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. It is understood that various differentcombinations of the above-listed steps can be used in various sequencesor in parallel, and there is no particular step that is critical orrequired. Also, features illustrated and discussed above with respect tosome embodiments can be combined with features illustrated and discussedabove with respect to other embodiments. Accordingly, all suchmodifications are intended to be included within the scope of thisinvention.

Several different advantages exist with these and other embodimentsdisclosed in the present disclosure. In addition to providing a methodfor patterning a photosensitive layer that may be implemented even asprocess technologies progress to 45 nm and below, the method disclosedherein does not require advance photolithography techniques and/orphotosensitive materials. Also, the method disclosed herein utilizes adouble exposure and single etch process to pattern features thereby,reducing the complexity and costs of fabricating semiconductor devices.The method disclosed herein may form line and/or hole patterns that haveimproved profiles and critical dimension uniformity.

1-20. (canceled)
 21. A method comprising: treating a substrate with oneof boron cations and hydrogen cations; forming a patterned firstmaterial layer over the substrate; treating the patterned first materiallayer with additional cations; forming a patterned second material layerover the substrate; and processing the substrate using the first andsecond patterns as a mask.
 22. The method of claim 21, wherein thepatterned first material layer includes a first photoresist material andthe patterned second material layer includes a second photoresistmaterial.
 23. The method of claim 21, wherein treating the substratewith one of boron cations and hydrogen cations including performing oneof a cation implantation process and a plasma treatment.
 24. The methodof claim 21, further comprising forming a third material layer over thesubstrate, the third material layer being different from the patternedfirst material layer and the patterned second material layer.
 25. Themethod of claim 24, wherein treating the substrate with one of boroncations and hydrogen cations includes treating the third material layerwith one of boron cations and hydrogen cations.
 26. The method of claim24, wherein forming the third material layer over the substrate includesforming the third material over the substrate prior to forming thepatterned first material layer over the substrate.
 27. The method ofclaim 26, wherein the third material layer is in direct contact with thesubstrate, and wherein the patterned first material layer is in directcontact with the third material layer.
 28. A method comprising:providing a substrate including a material layer formed thereon;treating the substrate including the material layer with a first cationselected from the group consisting of B, H, Al, Ga, In, N, P, As, Sb, C,Si, Ge, Sn, He, F, Br, Ne, and Ar; forming a first photoresist layerover the material layer; and patterning the first photoresist layer toform a first pattern.
 29. The method of clam 28, further comprisingtreating the first pattern with a second cation.
 30. The method of claim29, wherein the second cation is selected from the group consisting ofB, H, Al, Ga, In, N, P, As, Sb, C, Si, Ge, Sn, He, Cl, O, F, Cl, Br, Ne,and Ar.
 31. The method of claim 28, wherein the material layer includesat least one of silicon, silicon oxide, silicon oxynitride, organicmaterial, conductive material, and low-k dielectric material.
 32. Themethod of claim 28, further comprising: forming a second photoresistlayer over the first pattern; and patterning the second photoresistlayer to form a second pattern.
 33. The method of claim 32, furthercomprising processing the material layer using the first and secondpatterns as a mask.
 34. A method comprising: treating a substrate with afirst cation selected from the group consisting of Boron and Hydrogen;forming a first photosensitive layer over the substrate; patterning thefirst photosensitive layer to form a first pattern; and processing thesubstrate using the first pattern as a mask.
 35. The method of claim 34,further comprising forming a material layer over the substrate prior totreating the substrate with the first cation.
 36. The method of claim34, wherein the material layer is formed of a material selected from thegroup consisting of a silicon, silicon oxide (SiO2), low-k dielectricmaterial, organic material, conductive material, and silicon oxynitride(SiON).
 37. The method of claim 34, further comprising treating thefirst photosensitive layer with a second cation.
 38. The method of claim34, further comprising: forming a second photoresist layer over thefirst pattern; patterning the second photoresist layer to form a secondpattern, and wherein processing the substrate includes using the firstand second patterns as the mask.
 39. The method of claim 34, furthercomprising: forming a second material layer over the first pattern;patterning the second material layer to form a second pattern, andwherein processing the substrate includes using the first and secondpatterns as the mask.
 40. The method of claim 34, wherein forming thefirst photosensitive layer over the substrate occurs after treating thesubstrate with the first cation.